Field of the Invention
The invention relates to an integrated soft shell reservoir having a rib member positioned adjacent an outlet port to force an attached flexible membrane to bridge the outlet port and facilitate drainage of the reservoir.
Blood heaters, blood reservoirs and membrane oxygenators of various types are known and have been used in the past in the oxygenation of blood during surgery. One such type of unitary assembly with rigid reservoir, heater and a hollow fiber blood oxygenator is disclosed in U.S. Pat. No. 4,424,190.
In this system, and expansible blood reservoir is provided having a rigid self-supporting, concave shell and an integrally attached flexible membrane or complement member which forms a variable volume blood reservoir. The reservoir is constructed of transparent or translucent materials and arranged such that the blood in the reservoir is at all times visible to the technician during use for easy observation of the blood level. As is common in this device and others like it, the reservoir is provided with blood inlet means and blood outlet means. The blood outlet means is constructed with respect to size and location relative to the blood inlet means as to ensure a low exit of blood flow velocity.
A disadvantage with this type of reservoir is that the blood outlet port located at the base or bottom of the reservoir closes off and prevents blood drainage when a pucker forms in the receding flexible membrane. In other words, as the blood is draining out of the reservoir through the blood outlet port, the membrane begins to draw up and fold. As the fold gets in close proximity to the suction at the outlet port, the puckering membrane closes off the outlet port before the reservoir is completely drained.